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class="link-text" data-v-2cfe069a>01.基础入门</span><!--]--><!----></a><!----><!--]--><!--[--><a class="VPLink link link" href="/articles/rust/02.%E5%9F%BA%E7%A1%80%E8%AF%AD%E6%B3%95.html" style="padding-left:0px;" data-v-2cfe069a data-v-3c355974><!--[--><span class="link-text" data-v-2cfe069a>02.基础语法</span><!--]--><!----></a><!----><!--]--><!--[--><a class="VPLink link link" href="/articles/rust/03.%E6%8C%87%E9%92%88%E4%B8%8E%E5%86%85%E5%AD%98%E5%88%86%E9%85%8D.html" style="padding-left:0px;" data-v-2cfe069a data-v-3c355974><!--[--><span class="link-text" data-v-2cfe069a>03.指针与内存分配</span><!--]--><!----></a><!----><!--]--><!--[--><a class="VPLink link link" href="/articles/rust/04.%E7%A8%8B%E5%BA%8F%E7%BB%93%E6%9E%84%E5%92%8C%E5%BC%82%E5%B8%B8%E5%A4%84%E7%90%86.html" style="padding-left:0px;" data-v-2cfe069a data-v-3c355974><!--[--><span class="link-text" data-v-2cfe069a>04.程序结构和异常处理</span><!--]--><!----></a><!----><!--]--><!--[--><a class="VPLink link link" href="/articles/rust/05.%E6%95%B0%E6%8D%AE%E7%BB%93%E6%9E%84%E4%B8%8E%E6%B3%9B%E5%9E%8B.html" style="padding-left:0px;" data-v-2cfe069a data-v-3c355974><!--[--><span class="link-text" data-v-2cfe069a>05.数据结构与泛型</span><!--]--><!----></a><!----><!--]--><!--[--><a class="VPLink link link" href="/articles/rust/06.trait%E4%B8%8E%E7%94%9F%E5%91%BD%E5%91%A8%E6%9C%9F.html" style="padding-left:0px;" data-v-2cfe069a data-v-3c355974><!--[--><span class="link-text" data-v-2cfe069a>06.trait与生命周期</span><!--]--><!----></a><!----><!--]--><!--[--><a class="VPLink link link" href="/articles/rust/07.%E7%BC%96%E5%86%99%E6%B5%8B%E8%AF%95.html" style="padding-left:0px;" data-v-2cfe069a data-v-3c355974><!--[--><span class="link-text" data-v-2cfe069a>07.编写测试</span><!--]--><!----></a><!----><!--]--><!--[--><a class="VPLink link link" href="/articles/rust/08.%E6%9E%84%E5%BB%BA%E5%91%BD%E4%BB%A4%E8%A1%8C%E7%A8%8B%E5%BA%8F.html" style="padding-left:0px;" data-v-2cfe069a data-v-3c355974><!--[--><span class="link-text" data-v-2cfe069a>08.构建命令行程序</span><!--]--><!----></a><!----><!--]--><!--[--><a class="VPLink link link" href="/articles/rust/09.%E9%97%AD%E5%8C%85%E4%B8%8E%E8%BF%AD%E4%BB%A3%E5%99%A8.html" style="padding-left:0px;" data-v-2cfe069a data-v-3c355974><!--[--><span class="link-text" data-v-2cfe069a>09.闭包与迭代器</span><!--]--><!----></a><!----><!--]--><!--[--><a class="VPLink link link" href="/articles/rust/10.%E5%8F%91%E5%B8%83%E9%A1%B9%E7%9B%AE.html" style="padding-left:0px;" data-v-2cfe069a data-v-3c355974><!--[--><span class="link-text" data-v-2cfe069a>10.发布项目</span><!--]--><!----></a><!----><!--]--><!--[--><a class="VPLink link link" href="/articles/rust/11.%E6%99%BA%E8%83%BD%E6%8C%87%E9%92%88.html" style="padding-left:0px;" data-v-2cfe069a data-v-3c355974><!--[--><span class="link-text" data-v-2cfe069a>11.智能指针</span><!--]--><!----></a><!----><!--]--><!--[--><a class="VPLink link link" href="/articles/rust/12.%E5%B9%B6%E5%8F%91.html" style="padding-left:0px;" data-v-2cfe069a data-v-3c355974><!--[--><span class="link-text" data-v-2cfe069a>12.并发</span><!--]--><!----></a><!----><!--]--><!--[--><a class="VPLink link link" href="/articles/rust/13.%E9%9D%A2%E5%90%91%E5%AF%B9%E8%B1%A1.html" style="padding-left:0px;" data-v-2cfe069a data-v-3c355974><!--[--><span class="link-text" data-v-2cfe069a>13.面向对象</span><!--]--><!----></a><!----><!--]--><!--[--><a class="VPLink link link" href="/articles/rust/14.%E4%B8%8D%E5%AE%89%E5%85%A8Rust.html" style="padding-left:0px;" data-v-2cfe069a data-v-3c355974><!--[--><span class="link-text" data-v-2cfe069a>14.不安全Rust</span><!--]--><!----></a><!----><!--]--><!--[--><a class="VPLink link link" href="/articles/rust/15.%E9%AB%98%E7%BA%A7%E7%89%B9%E6%80%A7.html" style="padding-left:0px;" data-v-2cfe069a data-v-3c355974><!--[--><span class="link-text" data-v-2cfe069a>15.高级特性</span><!--]--><!----></a><!----><!--]--><!--[--><a class="VPLink link link" href="/articles/rust/16.%E6%89%8B%E5%86%99web%E6%9C%8D%E5%8A%A1%E5%99%A8%E5%92%8C%E7%BA%BF%E7%A8%8B%E6%B1%A0.html" style="padding-left:0px;" data-v-2cfe069a data-v-3c355974><!--[--><span class="link-text" data-v-2cfe069a>16.手写web服务器和线程池</span><!--]--><!----></a><!----><!--]--><!--[--><a class="VPLink link link" href="/articles/rust/17.rust%E5%BC%82%E6%AD%A5%E7%BC%96%E7%A8%8B.html" style="padding-left:0px;" data-v-2cfe069a data-v-3c355974><!--[--><span class="link-text" data-v-2cfe069a>17.rust异步编程</span><!--]--><!----></a><!----><!--]--><!--]--></div></section></div><div class="group" data-v-f332cb62><section class="VPSidebarGroup collapsible" data-v-f332cb62 data-v-2976c796><div class="title" role="button" data-v-2976c796><h2 class="title-text" data-v-2976c796>rustweb</h2><div class="action" data-v-2976c796><svg xmlns="http://www.w3.org/2000/svg" xmlns:xlink="http://www.w3.org/1999/xlink" viewbox="0 0 24 24" class="icon minus" data-v-2976c796><path 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server</span><!--]--><!----></a><!----><!--]--><!--[--><a class="VPLink link link" href="/articles/rustweb/02.Actix.html" style="padding-left:0px;" data-v-2cfe069a data-v-3c355974><!--[--><span class="link-text" data-v-2cfe069a>02.Actix</span><!--]--><!----></a><!----><!--]--><!--[--><a class="VPLink link link" href="/articles/rustweb/03.%E8%BF%9E%E6%8E%A5%E6%95%B0%E6%8D%AE%E5%BA%93.html" style="padding-left:0px;" data-v-2cfe069a data-v-3c355974><!--[--><span class="link-text" data-v-2cfe069a>03.连接数据库</span><!--]--><!----></a><!----><!--]--><!--[--><a class="VPLink link link active" href="/articles/rustweb/04.%E9%94%99%E8%AF%AF%E5%A4%84%E7%90%86.html" style="padding-left:0px;" data-v-2cfe069a data-v-3c355974><!--[--><span class="link-text" data-v-2cfe069a>04.错误处理</span><!--]--><!----></a><!----><!--]--><!--[--><a class="VPLink link link" href="/articles/rustweb/05.%E5%AE%8C%E6%95%B4%E9%A1%B9%E7%9B%AE%E9%87%8D%E6%9E%84.html" style="padding-left:0px;" data-v-2cfe069a data-v-3c355974><!--[--><span class="link-text" data-v-2cfe069a>05.完整项目重构</span><!--]--><!----></a><!----><!--]--><!--[--><a class="VPLink link link" href="/articles/rustweb/06.%E6%9C%8D%E5%8A%A1%E5%99%A8%E7%AB%AFweb%E5%BA%94%E7%94%A8.html" style="padding-left:0px;" data-v-2cfe069a data-v-3c355974><!--[--><span class="link-text" data-v-2cfe069a>06.服务器端web应用</span><!--]--><!----></a><!----><!--]--><!--[--><a class="VPLink link link" href="/articles/rustweb/07.WebAssembly.html" style="padding-left:0px;" data-v-2cfe069a data-v-3c355974><!--[--><span class="link-text" data-v-2cfe069a>07.WebAssembly</span><!--]--><!----></a><!----><!--]--><!--[--><a class="VPLink link link" href="/articles/rustweb/08.%E5%8F%91%E5%B8%83.html" style="padding-left:0px;" data-v-2cfe069a data-v-3c355974><!--[--><span class="link-text" data-v-2cfe069a>08.发布</span><!--]--><!----></a><!----><!--]--><!--]--></div></section></div><!--]--></nav></aside><div class="VPContent has-sidebar" id="VPContent" data-v-c6a644e1 data-v-c95df128><div class="VPDoc has-sidebar has-aside" data-v-c95df128 data-v-37ebe389><div class="container" data-v-37ebe389><div class="aside" data-v-37ebe389><div class="aside-curtain" data-v-37ebe389></div><div class="aside-container" data-v-37ebe389><div class="aside-content" data-v-37ebe389><div class="VPDocAside" data-v-37ebe389 data-v-afc4c1a1><!--[--><!--]--><!--[--><!--]--><div class="VPDocAsideOutline" data-v-afc4c1a1 data-v-2865c0b0><div class="content" data-v-2865c0b0><div class="outline-marker" data-v-2865c0b0></div><div class="outline-title" data-v-2865c0b0>On this page</div><nav aria-labelledby="doc-outline-aria-label" data-v-2865c0b0><span class="visually-hidden" id="doc-outline-aria-label" data-v-2865c0b0> Table of Contents for current page </span><ul class="root" data-v-2865c0b0 data-v-1188541a><!--[--><!--]--></ul></nav></div></div><!--[--><!--]--><div class="spacer" data-v-afc4c1a1></div><!--[--><!--]--><!----><!--[--><!--]--><!--[--><!--]--></div></div></div></div><div class="content" data-v-37ebe389><div class="content-container" data-v-37ebe389><!--[--><!--]--><main class="main" data-v-37ebe389><div style="position:relative;" class="vp-doc _articles_rustweb_04_%E9%94%99%E8%AF%AF%E5%A4%84%E7%90%86" data-v-37ebe389><div><h1 id="rust-web入门（四）：错误处理" tabindex="-1">Rust Web入门（四）：错误处理 <a class="header-anchor" href="#rust-web入门（四）：错误处理" aria-hidden="true">#</a></h1><p>本教程笔记来自 杨旭老师的 rust web 全栈教程，链接如下：</p><p><a href="https://www.bilibili.com/video/BV1RP4y1G7KF?p=1&amp;vd_source=8595fbbf160cc11a0cc07cadacf22951" target="_blank" rel="noreferrer">https://www.bilibili.com/video/BV1RP4y1G7KF?p=1&amp;vd_source=8595fbbf160cc11a0cc07cadacf22951</a></p><p>学习 Rust Web 需要学习 rust 的前置知识可以学习杨旭老师的另一门教程</p><p><a href="https://www.bilibili.com/video/BV1hp4y1k7SV/?spm_id_from=333.999.0.0&amp;vd_source=8595fbbf160cc11a0cc07cadacf22951" target="_blank" rel="noreferrer">https://www.bilibili.com/video/BV1hp4y1k7SV/?spm_id_from=333.999.0.0&amp;vd_source=8595fbbf160cc11a0cc07cadacf22951</a></p><p>今天来入门基于 rust 的 web 怎么样处理错误：</p><h2 id="actix错误处理机制" tabindex="-1">Actix错误处理机制 <a class="header-anchor" href="#actix错误处理机制" aria-hidden="true">#</a></h2><p>actix 定义了一个通用的错误类型， actix_web::error::Error , 任何实现了 Error Trait 的类型，都可以通过 ? 运算转化为 Actix 的Error类型</p><p>如果在实现了 <code>ResponseError</code> trait 的 <code>Result</code> 中返回 <code>Error</code>，则 actix-web 会将该错误呈现为一个 HTTP 响应，并使用相应的状态码，能实现这个功能的包含了对常见的错误，如 IO错误，Serde 错误，Web 错误等</p><h2 id="自定义错误处理器" tabindex="-1">自定义错误处理器 <a class="header-anchor" href="#自定义错误处理器" aria-hidden="true">#</a></h2><p>在内置实现不可用的时候，可以自定义错误到 HTTP Respone。实现 ResponseError 来现实返回一个 HTTP 请求，具体如下：</p><p>我们首先自定义一个<code>error.rs</code> 来自定义我们的错误类型，我们创建一个枚举来列举我们可能出现的错误，在定义一个结构来存储我们返回给用户的响应的内容：</p><div class="language-rust"><button class="copy"></button><span class="lang">rust</span><pre><code><span class="line"><span style="color:#F78C6C;">use</span><span style="color:#FFCB6B;"> actix_web</span><span style="color:#89DDFF;">::{</span><span style="color:#FFCB6B;">error</span><span style="color:#89DDFF;">,</span><span style="color:#FFCB6B;"> http</span><span style="color:#89DDFF;">::</span><span style="color:#FFCB6B;">StatusCode</span><span style="color:#89DDFF;">,</span><span style="color:#FFCB6B;"> HttpResponse</span><span style="color:#89DDFF;">,</span><span style="color:#FFCB6B;"> Result</span><span style="color:#89DDFF;">};</span></span>
<span class="line"><span style="color:#F78C6C;">use</span><span style="color:#FFCB6B;"> serde</span><span style="color:#89DDFF;">::</span><span style="color:#FFCB6B;">Serialize</span><span style="color:#89DDFF;">;</span></span>
<span class="line"><span style="color:#F78C6C;">use</span><span style="color:#FFCB6B;"> sqlx</span><span style="color:#89DDFF;">::</span><span style="color:#FFCB6B;">error</span><span style="color:#89DDFF;">::</span><span style="color:#FFCB6B;">Error </span><span style="color:#F78C6C;">as</span><span style="color:#FFCB6B;"> SQLxError</span><span style="color:#89DDFF;">;</span></span>
<span class="line"><span style="color:#F78C6C;">use</span><span style="color:#FFCB6B;"> std</span><span style="color:#89DDFF;">::</span><span style="color:#FFCB6B;">fmt</span><span style="color:#89DDFF;">;</span></span>
<span class="line"></span>
<span class="line"><span style="color:#F78C6C;">use</span><span style="color:#FFCB6B;"> actix_web</span><span style="color:#89DDFF;">::{</span><span style="color:#FFCB6B;">error</span><span style="color:#89DDFF;">,</span><span style="color:#FFCB6B;"> http</span><span style="color:#89DDFF;">::</span><span style="color:#FFCB6B;">StatusCode</span><span style="color:#89DDFF;">,</span><span style="color:#FFCB6B;"> HttpResponse</span><span style="color:#89DDFF;">,</span><span style="color:#FFCB6B;"> Result</span><span style="color:#89DDFF;">};</span></span>
<span class="line"><span style="color:#F78C6C;">use</span><span style="color:#FFCB6B;"> serde</span><span style="color:#89DDFF;">::</span><span style="color:#FFCB6B;">Serialize</span><span style="color:#89DDFF;">;</span></span>
<span class="line"><span style="color:#F78C6C;">use</span><span style="color:#FFCB6B;"> sqlx</span><span style="color:#89DDFF;">::</span><span style="color:#FFCB6B;">error</span><span style="color:#89DDFF;">::</span><span style="color:#FFCB6B;">Error </span><span style="color:#F78C6C;">as</span><span style="color:#FFCB6B;"> SQLxError</span><span style="color:#89DDFF;">;</span></span>
<span class="line"><span style="color:#F78C6C;">use</span><span style="color:#FFCB6B;"> std</span><span style="color:#89DDFF;">::</span><span style="color:#FFCB6B;">fmt</span><span style="color:#89DDFF;">;</span></span>
<span class="line"></span>
<span class="line"><span style="color:#89DDFF;">#[</span><span style="color:#A6ACCD;">derive</span><span style="color:#89DDFF;">(</span><span style="color:#FFCB6B;">Debug</span><span style="color:#89DDFF;">,</span><span style="color:#A6ACCD;"> </span><span style="color:#FFCB6B;">Serialize</span><span style="color:#89DDFF;">)]</span></span>
<span class="line"><span style="color:#F78C6C;">pub</span><span style="color:#A6ACCD;"> </span><span style="color:#C792EA;">enum</span><span style="color:#A6ACCD;"> </span><span style="color:#FFCB6B;">MyError</span><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">{</span></span>
<span class="line"><span style="color:#A6ACCD;">    </span><span style="color:#82AAFF;">DBError</span><span style="color:#89DDFF;">(</span><span style="color:#FFCB6B;">String</span><span style="color:#89DDFF;">),</span></span>
<span class="line"><span style="color:#A6ACCD;">    </span><span style="color:#82AAFF;">ActixError</span><span style="color:#89DDFF;">(</span><span style="color:#FFCB6B;">String</span><span style="color:#89DDFF;">),</span></span>
<span class="line"><span style="color:#A6ACCD;">    </span><span style="color:#89DDFF;">#[</span><span style="color:#A6ACCD;">allow</span><span style="color:#89DDFF;">(</span><span style="color:#A6ACCD;">dead_code</span><span style="color:#89DDFF;">)]</span></span>
<span class="line"><span style="color:#A6ACCD;">    </span><span style="color:#82AAFF;">NotFound</span><span style="color:#89DDFF;">(</span><span style="color:#FFCB6B;">String</span><span style="color:#89DDFF;">),</span></span>
<span class="line"><span style="color:#89DDFF;">}</span></span>
<span class="line"></span>
<span class="line"><span style="color:#89DDFF;">#[</span><span style="color:#A6ACCD;">derive</span><span style="color:#89DDFF;">(</span><span style="color:#FFCB6B;">Debug</span><span style="color:#89DDFF;">,</span><span style="color:#A6ACCD;"> </span><span style="color:#FFCB6B;">Serialize</span><span style="color:#89DDFF;">)]</span></span>
<span class="line"><span style="color:#F78C6C;">pub</span><span style="color:#A6ACCD;"> </span><span style="color:#C792EA;">struct</span><span style="color:#A6ACCD;"> </span><span style="color:#FFCB6B;">MyErrorResponse</span><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">{</span></span>
<span class="line"><span style="color:#A6ACCD;">    error_message</span><span style="color:#89DDFF;">:</span><span style="color:#A6ACCD;"> </span><span style="color:#FFCB6B;">String</span><span style="color:#89DDFF;">,</span></span>
<span class="line"><span style="color:#89DDFF;">}</span></span>
<span class="line"></span></code></pre></div><p>之后我们为 MyError 实现 <code>ResponseError</code> trait ，它包含一些方法，可以在错误发生的时候，将错误转化为一个 Http Respone 返回给用户：</p><p>error_response 返回一个给用户的响应信息，而 status_code 返回一个对应的状态码，通过传入一个 error，可以得到返回给用户的响应的具体内容，从而实现错误到 Http Respone 的转换：</p><div class="language-rust"><button class="copy"></button><span class="lang">rust</span><pre><code><span class="line"><span style="color:#F78C6C;">impl</span><span style="color:#A6ACCD;"> </span><span style="color:#FFCB6B;">MyError</span><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">{</span></span>
<span class="line"><span style="color:#A6ACCD;">    </span><span style="color:#F78C6C;">fn</span><span style="color:#A6ACCD;"> </span><span style="color:#82AAFF;">error_response</span><span style="color:#89DDFF;">(&amp;</span><span style="color:#A6ACCD;">self</span><span style="color:#89DDFF;">)</span><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">-&gt;</span><span style="color:#A6ACCD;"> </span><span style="color:#FFCB6B;">String</span><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">{</span></span>
<span class="line"><span style="color:#A6ACCD;">        </span><span style="color:#89DDFF;">match</span><span style="color:#A6ACCD;"> self </span><span style="color:#89DDFF;">{</span></span>
<span class="line"><span style="color:#A6ACCD;">            </span><span style="color:#FFCB6B;">MyError</span><span style="color:#89DDFF;">::</span><span style="color:#82AAFF;">DBError</span><span style="color:#89DDFF;">(</span><span style="color:#A6ACCD;">msg</span><span style="color:#89DDFF;">)</span><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">=&gt;</span><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">{</span></span>
<span class="line"><span style="color:#A6ACCD;">                </span><span style="color:#82AAFF;">println!</span><span style="color:#89DDFF;">(</span><span style="color:#89DDFF;">&quot;</span><span style="color:#C3E88D;">Database error occurred: </span><span style="color:#89DDFF;">{</span><span style="color:#C3E88D;">:?</span><span style="color:#89DDFF;">}&quot;</span><span style="color:#89DDFF;">,</span><span style="color:#A6ACCD;"> msg</span><span style="color:#89DDFF;">);</span></span>
<span class="line"><span style="color:#A6ACCD;">                </span><span style="color:#89DDFF;">&quot;</span><span style="color:#C3E88D;">Database error</span><span style="color:#89DDFF;">&quot;</span><span style="color:#89DDFF;">.</span><span style="color:#82AAFF;">into</span><span style="color:#89DDFF;">()</span></span>
<span class="line"><span style="color:#A6ACCD;">            </span><span style="color:#89DDFF;">}</span></span>
<span class="line"><span style="color:#A6ACCD;">            </span><span style="color:#FFCB6B;">MyError</span><span style="color:#89DDFF;">::</span><span style="color:#82AAFF;">ActixError</span><span style="color:#89DDFF;">(</span><span style="color:#A6ACCD;">msg</span><span style="color:#89DDFF;">)</span><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">=&gt;</span><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">{</span></span>
<span class="line"><span style="color:#A6ACCD;">                </span><span style="color:#82AAFF;">println!</span><span style="color:#89DDFF;">(</span><span style="color:#89DDFF;">&quot;</span><span style="color:#C3E88D;">Server error occurred: </span><span style="color:#89DDFF;">{</span><span style="color:#C3E88D;">:?</span><span style="color:#89DDFF;">}&quot;</span><span style="color:#89DDFF;">,</span><span style="color:#A6ACCD;"> msg</span><span style="color:#89DDFF;">);</span></span>
<span class="line"><span style="color:#A6ACCD;">                </span><span style="color:#89DDFF;">&quot;</span><span style="color:#C3E88D;">Internal server error</span><span style="color:#89DDFF;">&quot;</span><span style="color:#89DDFF;">.</span><span style="color:#82AAFF;">into</span><span style="color:#89DDFF;">()</span></span>
<span class="line"><span style="color:#A6ACCD;">            </span><span style="color:#89DDFF;">}</span></span>
<span class="line"><span style="color:#A6ACCD;">            </span><span style="color:#FFCB6B;">MyError</span><span style="color:#89DDFF;">::</span><span style="color:#82AAFF;">NotFound</span><span style="color:#89DDFF;">(</span><span style="color:#A6ACCD;">msg</span><span style="color:#89DDFF;">)</span><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">=&gt;</span><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">{</span></span>
<span class="line"><span style="color:#A6ACCD;">                </span><span style="color:#82AAFF;">println!</span><span style="color:#89DDFF;">(</span><span style="color:#89DDFF;">&quot;</span><span style="color:#C3E88D;">Not found error occurred: </span><span style="color:#89DDFF;">{</span><span style="color:#C3E88D;">:?</span><span style="color:#89DDFF;">}&quot;</span><span style="color:#89DDFF;">,</span><span style="color:#A6ACCD;"> msg</span><span style="color:#89DDFF;">);</span></span>
<span class="line"><span style="color:#A6ACCD;">                msg</span><span style="color:#89DDFF;">.</span><span style="color:#82AAFF;">into</span><span style="color:#89DDFF;">()</span></span>
<span class="line"><span style="color:#A6ACCD;">            </span><span style="color:#89DDFF;">}</span></span>
<span class="line"><span style="color:#A6ACCD;">        </span><span style="color:#89DDFF;">}</span></span>
<span class="line"><span style="color:#A6ACCD;">    </span><span style="color:#89DDFF;">}</span></span>
<span class="line"><span style="color:#89DDFF;">}</span></span>
<span class="line"></span>
<span class="line"><span style="color:#F78C6C;">impl</span><span style="color:#A6ACCD;"> </span><span style="color:#FFCB6B;">error</span><span style="color:#89DDFF;">::</span><span style="color:#FFCB6B;">ResponseError</span><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">for</span><span style="color:#A6ACCD;"> </span><span style="color:#FFCB6B;">MyError</span><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">{</span></span>
<span class="line"><span style="color:#A6ACCD;">    </span><span style="color:#F78C6C;">fn</span><span style="color:#A6ACCD;"> </span><span style="color:#82AAFF;">status_code</span><span style="color:#89DDFF;">(&amp;</span><span style="color:#A6ACCD;">self</span><span style="color:#89DDFF;">)</span><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">-&gt;</span><span style="color:#A6ACCD;"> </span><span style="color:#FFCB6B;">StatusCode</span><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">{</span></span>
<span class="line"><span style="color:#A6ACCD;">        </span><span style="color:#89DDFF;">match</span><span style="color:#A6ACCD;"> self </span><span style="color:#89DDFF;">{</span></span>
<span class="line"><span style="color:#A6ACCD;">            </span><span style="color:#FFCB6B;">MyError</span><span style="color:#89DDFF;">::</span><span style="color:#82AAFF;">DBError</span><span style="color:#89DDFF;">(</span><span style="color:#A6ACCD;">_msg</span><span style="color:#89DDFF;">)</span><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">|</span><span style="color:#A6ACCD;"> </span><span style="color:#FFCB6B;">MyError</span><span style="color:#89DDFF;">::</span><span style="color:#82AAFF;">ActixError</span><span style="color:#89DDFF;">(</span><span style="color:#A6ACCD;">_msg</span><span style="color:#89DDFF;">)</span><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">=&gt;</span><span style="color:#A6ACCD;"> </span><span style="color:#FFCB6B;">StatusCode</span><span style="color:#89DDFF;">::</span><span style="color:#A6ACCD;">INTERNAL_SERVER_ERROR</span><span style="color:#89DDFF;">,</span></span>
<span class="line"><span style="color:#A6ACCD;">            </span><span style="color:#FFCB6B;">MyError</span><span style="color:#89DDFF;">::</span><span style="color:#82AAFF;">NotFound</span><span style="color:#89DDFF;">(</span><span style="color:#A6ACCD;">_msg</span><span style="color:#89DDFF;">)</span><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">=&gt;</span><span style="color:#A6ACCD;"> </span><span style="color:#FFCB6B;">StatusCode</span><span style="color:#89DDFF;">::</span><span style="color:#A6ACCD;">NOT_FOUND</span><span style="color:#89DDFF;">,</span></span>
<span class="line"><span style="color:#A6ACCD;">        </span><span style="color:#89DDFF;">}</span></span>
<span class="line"><span style="color:#A6ACCD;">    </span><span style="color:#89DDFF;">}</span></span>
<span class="line"></span>
<span class="line"><span style="color:#A6ACCD;">    </span><span style="color:#F78C6C;">fn</span><span style="color:#A6ACCD;"> </span><span style="color:#82AAFF;">error_response</span><span style="color:#89DDFF;">(&amp;</span><span style="color:#A6ACCD;">self</span><span style="color:#89DDFF;">)</span><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">-&gt;</span><span style="color:#A6ACCD;"> </span><span style="color:#FFCB6B;">HttpResponse</span><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">{</span></span>
<span class="line"><span style="color:#A6ACCD;">        </span><span style="color:#FFCB6B;">HttpResponse</span><span style="color:#89DDFF;">::</span><span style="color:#82AAFF;">build</span><span style="color:#89DDFF;">(</span><span style="color:#A6ACCD;">self</span><span style="color:#89DDFF;">.</span><span style="color:#82AAFF;">status_code</span><span style="color:#89DDFF;">()).</span><span style="color:#82AAFF;">json</span><span style="color:#89DDFF;">(</span><span style="color:#FFCB6B;">MyErrorResponse</span><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">{</span></span>
<span class="line"><span style="color:#A6ACCD;">            error_message</span><span style="color:#89DDFF;">:</span><span style="color:#A6ACCD;"> self</span><span style="color:#89DDFF;">.</span><span style="color:#82AAFF;">error_response</span><span style="color:#89DDFF;">(),</span></span>
<span class="line"><span style="color:#A6ACCD;">        </span><span style="color:#89DDFF;">})</span></span>
<span class="line"><span style="color:#A6ACCD;">    </span><span style="color:#89DDFF;">}</span></span>
<span class="line"><span style="color:#89DDFF;">}</span></span>
<span class="line"></span>
<span class="line"></span></code></pre></div><p>因为 error::ResponseError 这个接口还需要我们实现 Debug 和 Display ，所以我们加上 Display 的实现：</p><div class="language-rust"><button class="copy"></button><span class="lang">rust</span><pre><code><span class="line"><span style="color:#F78C6C;">impl</span><span style="color:#A6ACCD;"> </span><span style="color:#FFCB6B;">fmt</span><span style="color:#89DDFF;">::</span><span style="color:#FFCB6B;">Display</span><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">for</span><span style="color:#A6ACCD;"> </span><span style="color:#FFCB6B;">MyError</span><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">{</span></span>
<span class="line"><span style="color:#A6ACCD;">    </span><span style="color:#F78C6C;">fn</span><span style="color:#A6ACCD;"> </span><span style="color:#82AAFF;">fmt</span><span style="color:#89DDFF;">(&amp;</span><span style="color:#A6ACCD;">self</span><span style="color:#89DDFF;">,</span><span style="color:#A6ACCD;"> f</span><span style="color:#89DDFF;">:</span><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">&amp;</span><span style="color:#C792EA;">mut</span><span style="color:#A6ACCD;"> </span><span style="color:#FFCB6B;">fmt</span><span style="color:#89DDFF;">::</span><span style="color:#FFCB6B;">Formatter</span><span style="color:#89DDFF;">)</span><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">-&gt;</span><span style="color:#A6ACCD;"> </span><span style="color:#FFCB6B;">Result</span><span style="color:#89DDFF;">&lt;(),</span><span style="color:#A6ACCD;"> fmt</span><span style="color:#89DDFF;">::</span><span style="color:#FFCB6B;">Error</span><span style="color:#89DDFF;">&gt;</span><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">{</span></span>
<span class="line"><span style="color:#A6ACCD;">        </span><span style="color:#82AAFF;">write!</span><span style="color:#89DDFF;">(</span><span style="color:#A6ACCD;">f</span><span style="color:#89DDFF;">,</span><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">&quot;{}&quot;</span><span style="color:#89DDFF;">,</span><span style="color:#A6ACCD;"> self</span><span style="color:#89DDFF;">)</span></span>
<span class="line"><span style="color:#A6ACCD;">    </span><span style="color:#89DDFF;">}</span></span>
<span class="line"><span style="color:#89DDFF;">}</span></span>
<span class="line"></span></code></pre></div><p>最后，我们需要将原生的错误类型接入到我们的错误处理中，我们为原生的错误类型实现 <code>From&lt;T&gt;</code> ，当发生原生错误的时候，它就会转化为我们枚举里定义的错误，然后根据我们的代码返回：</p><div class="language-rust"><button class="copy"></button><span class="lang">rust</span><pre><code><span class="line"><span style="color:#F78C6C;">impl</span><span style="color:#A6ACCD;"> </span><span style="color:#FFCB6B;">From</span><span style="color:#89DDFF;">&lt;</span><span style="color:#A6ACCD;">actix_web</span><span style="color:#89DDFF;">::</span><span style="color:#A6ACCD;">error</span><span style="color:#89DDFF;">::</span><span style="color:#FFCB6B;">Error</span><span style="color:#89DDFF;">&gt;</span><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">for</span><span style="color:#A6ACCD;"> </span><span style="color:#FFCB6B;">MyError</span><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">{</span></span>
<span class="line"><span style="color:#A6ACCD;">    </span><span style="color:#F78C6C;">fn</span><span style="color:#A6ACCD;"> </span><span style="color:#82AAFF;">from</span><span style="color:#89DDFF;">(</span><span style="color:#A6ACCD;">err</span><span style="color:#89DDFF;">:</span><span style="color:#A6ACCD;"> </span><span style="color:#FFCB6B;">actix_web</span><span style="color:#89DDFF;">::</span><span style="color:#FFCB6B;">error</span><span style="color:#89DDFF;">::</span><span style="color:#FFCB6B;">Error</span><span style="color:#89DDFF;">)</span><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">-&gt;</span><span style="color:#A6ACCD;"> Self </span><span style="color:#89DDFF;">{</span></span>
<span class="line"><span style="color:#A6ACCD;">        </span><span style="color:#FFCB6B;">MyError</span><span style="color:#89DDFF;">::</span><span style="color:#82AAFF;">ActixError</span><span style="color:#89DDFF;">(</span><span style="color:#A6ACCD;">err</span><span style="color:#89DDFF;">.</span><span style="color:#82AAFF;">to_string</span><span style="color:#89DDFF;">())</span></span>
<span class="line"><span style="color:#A6ACCD;">    </span><span style="color:#89DDFF;">}</span></span>
<span class="line"><span style="color:#89DDFF;">}</span></span>
<span class="line"></span>
<span class="line"><span style="color:#F78C6C;">impl</span><span style="color:#A6ACCD;"> </span><span style="color:#FFCB6B;">From</span><span style="color:#89DDFF;">&lt;</span><span style="color:#FFCB6B;">SQLxError</span><span style="color:#89DDFF;">&gt;</span><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">for</span><span style="color:#A6ACCD;"> </span><span style="color:#FFCB6B;">MyError</span><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">{</span></span>
<span class="line"><span style="color:#A6ACCD;">    </span><span style="color:#F78C6C;">fn</span><span style="color:#A6ACCD;"> </span><span style="color:#82AAFF;">from</span><span style="color:#89DDFF;">(</span><span style="color:#A6ACCD;">err</span><span style="color:#89DDFF;">:</span><span style="color:#A6ACCD;"> </span><span style="color:#FFCB6B;">SQLxError</span><span style="color:#89DDFF;">)</span><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">-&gt;</span><span style="color:#A6ACCD;"> Self </span><span style="color:#89DDFF;">{</span></span>
<span class="line"><span style="color:#A6ACCD;">        </span><span style="color:#FFCB6B;">MyError</span><span style="color:#89DDFF;">::</span><span style="color:#82AAFF;">DBError</span><span style="color:#89DDFF;">(</span><span style="color:#A6ACCD;">err</span><span style="color:#89DDFF;">.</span><span style="color:#82AAFF;">to_string</span><span style="color:#89DDFF;">())</span></span>
<span class="line"><span style="color:#A6ACCD;">    </span><span style="color:#89DDFF;">}</span></span>
<span class="line"><span style="color:#89DDFF;">}</span></span>
<span class="line"></span></code></pre></div><h2 id="为项目添加错误处理" tabindex="-1">为项目添加错误处理 <a class="header-anchor" href="#为项目添加错误处理" aria-hidden="true">#</a></h2><p>现在我们有了一个错误处理的类，我们需要把它用在我们的代码中，因为我们之前说过，任何实现了 Error Trait 的类型，都可以通过 ? 运算转化为 Actix 的 Error 类型，所以我们将之前所有的 unwarp() 替换成 ? 运算即可</p><p>同时，我们的返回值就需要改成 Result 类型，成功时返回一个 Ok 包裹数据，失败的时候则通过 ？ 运算返回一个 error 类型，而数据库的 error 已经包装进了我们的 MyError 中，所以会自动转化为一个 MyError ：</p><div class="language-rust"><button class="copy"></button><span class="lang">rust</span><pre><code><span class="line"><span style="color:#F78C6C;">use</span><span style="color:#FFCB6B;"> </span><span style="color:#A6ACCD;">super</span><span style="color:#89DDFF;">::</span><span style="color:#FFCB6B;">error</span><span style="color:#89DDFF;">::</span><span style="color:#FFCB6B;">MyError</span><span style="color:#89DDFF;">;</span></span>
<span class="line"><span style="color:#F78C6C;">use</span><span style="color:#FFCB6B;"> </span><span style="color:#F78C6C;">crate</span><span style="color:#89DDFF;">::</span><span style="color:#FFCB6B;">models</span><span style="color:#89DDFF;">::*;</span></span>
<span class="line"><span style="color:#F78C6C;">use</span><span style="color:#FFCB6B;"> sqlx</span><span style="color:#89DDFF;">::</span><span style="color:#FFCB6B;">mysql</span><span style="color:#89DDFF;">::</span><span style="color:#FFCB6B;">MySqlPool</span><span style="color:#89DDFF;">;</span></span>
<span class="line"></span>
<span class="line"><span style="color:#F78C6C;">pub</span><span style="color:#A6ACCD;"> </span><span style="color:#F78C6C;">async</span><span style="color:#A6ACCD;"> </span><span style="color:#F78C6C;">fn</span><span style="color:#A6ACCD;"> </span><span style="color:#82AAFF;">get_courses_for_teacher_db</span><span style="color:#89DDFF;">(</span></span>
<span class="line"><span style="color:#A6ACCD;">    pool</span><span style="color:#89DDFF;">:</span><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">&amp;</span><span style="color:#FFCB6B;">MySqlPool</span><span style="color:#89DDFF;">,</span></span>
<span class="line"><span style="color:#A6ACCD;">    teacher_id</span><span style="color:#89DDFF;">:</span><span style="color:#A6ACCD;"> </span><span style="color:#FFCB6B;">i32</span><span style="color:#89DDFF;">,</span></span>
<span class="line"><span style="color:#89DDFF;">)</span><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">-&gt;</span><span style="color:#A6ACCD;"> </span><span style="color:#FFCB6B;">Result</span><span style="color:#89DDFF;">&lt;</span><span style="color:#FFCB6B;">Vec</span><span style="color:#89DDFF;">&lt;</span><span style="color:#FFCB6B;">Course</span><span style="color:#89DDFF;">&gt;,</span><span style="color:#A6ACCD;"> </span><span style="color:#FFCB6B;">MyError</span><span style="color:#89DDFF;">&gt;</span><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">{</span></span>
<span class="line"><span style="color:#A6ACCD;">    </span><span style="color:#C792EA;">let</span><span style="color:#A6ACCD;"> rows </span><span style="color:#89DDFF;">=</span><span style="color:#A6ACCD;"> </span><span style="color:#FFCB6B;">sqlx</span><span style="color:#89DDFF;">::</span><span style="color:#82AAFF;">query!</span><span style="color:#89DDFF;">(</span></span>
<span class="line"><span style="color:#A6ACCD;">        </span><span style="color:#89DDFF;">&quot;</span><span style="color:#C3E88D;">SELECT id, teacher_id, name, time</span></span>
<span class="line"><span style="color:#C3E88D;">        FROM course</span></span>
<span class="line"><span style="color:#C3E88D;">        WHERE teacher_id = ?</span><span style="color:#89DDFF;">&quot;</span><span style="color:#89DDFF;">,</span></span>
<span class="line"><span style="color:#A6ACCD;">        teacher_id</span></span>
<span class="line"><span style="color:#A6ACCD;">    </span><span style="color:#89DDFF;">)</span></span>
<span class="line"><span style="color:#A6ACCD;">    </span><span style="color:#89DDFF;">.</span><span style="color:#82AAFF;">fetch_all</span><span style="color:#89DDFF;">(</span><span style="color:#A6ACCD;">pool</span><span style="color:#89DDFF;">)</span></span>
<span class="line"><span style="color:#A6ACCD;">    </span><span style="color:#89DDFF;">.</span><span style="color:#89DDFF;">await</span><span style="color:#89DDFF;">?;</span></span>
<span class="line"></span>
<span class="line"><span style="color:#A6ACCD;">    </span><span style="color:#C792EA;">let</span><span style="color:#A6ACCD;"> courses</span><span style="color:#89DDFF;">:</span><span style="color:#A6ACCD;"> </span><span style="color:#FFCB6B;">Vec</span><span style="color:#89DDFF;">&lt;</span><span style="color:#FFCB6B;">Course</span><span style="color:#89DDFF;">&gt;</span><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">=</span><span style="color:#A6ACCD;"> rows</span></span>
<span class="line"><span style="color:#A6ACCD;">        </span><span style="color:#89DDFF;">.</span><span style="color:#82AAFF;">iter</span><span style="color:#89DDFF;">()</span></span>
<span class="line"><span style="color:#A6ACCD;">        </span><span style="color:#89DDFF;">.</span><span style="color:#82AAFF;">map</span><span style="color:#89DDFF;">(|</span><span style="color:#A6ACCD;">r</span><span style="color:#89DDFF;">|</span><span style="color:#A6ACCD;"> </span><span style="color:#FFCB6B;">Course</span><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">{</span></span>
<span class="line"><span style="color:#A6ACCD;">            id</span><span style="color:#89DDFF;">:</span><span style="color:#A6ACCD;"> </span><span style="color:#FFCB6B;">Some</span><span style="color:#89DDFF;">(</span><span style="color:#A6ACCD;">r</span><span style="color:#89DDFF;">.</span><span style="color:#A6ACCD;">id</span><span style="color:#89DDFF;">),</span></span>
<span class="line"><span style="color:#A6ACCD;">            teacher_id</span><span style="color:#89DDFF;">:</span><span style="color:#A6ACCD;"> r</span><span style="color:#89DDFF;">.</span><span style="color:#A6ACCD;">teacher_id</span><span style="color:#89DDFF;">,</span></span>
<span class="line"><span style="color:#A6ACCD;">            name</span><span style="color:#89DDFF;">:</span><span style="color:#A6ACCD;"> r</span><span style="color:#89DDFF;">.</span><span style="color:#A6ACCD;">name</span><span style="color:#89DDFF;">.</span><span style="color:#82AAFF;">clone</span><span style="color:#89DDFF;">(),</span></span>
<span class="line"><span style="color:#A6ACCD;">            time</span><span style="color:#89DDFF;">:</span><span style="color:#A6ACCD;"> </span><span style="color:#FFCB6B;">Some</span><span style="color:#89DDFF;">(</span><span style="color:#A6ACCD;">r</span><span style="color:#89DDFF;">.</span><span style="color:#A6ACCD;">time</span><span style="color:#89DDFF;">.</span><span style="color:#82AAFF;">unwrap</span><span style="color:#89DDFF;">()),</span></span>
<span class="line"><span style="color:#A6ACCD;">        </span><span style="color:#89DDFF;">})</span></span>
<span class="line"><span style="color:#A6ACCD;">        </span><span style="color:#89DDFF;">.</span><span style="color:#82AAFF;">collect</span><span style="color:#89DDFF;">();</span></span>
<span class="line"><span style="color:#A6ACCD;">    </span><span style="color:#89DDFF;">match</span><span style="color:#A6ACCD;"> courses</span><span style="color:#89DDFF;">.</span><span style="color:#82AAFF;">len</span><span style="color:#89DDFF;">()</span><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">{</span></span>
<span class="line"><span style="color:#A6ACCD;">        </span><span style="color:#F78C6C;">0</span><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">=&gt;</span><span style="color:#A6ACCD;"> </span><span style="color:#FFCB6B;">Err</span><span style="color:#89DDFF;">(</span><span style="color:#FFCB6B;">MyError</span><span style="color:#89DDFF;">::</span><span style="color:#82AAFF;">NotFound</span><span style="color:#89DDFF;">(</span><span style="color:#89DDFF;">&quot;</span><span style="color:#C3E88D;">Course not found for teacher</span><span style="color:#89DDFF;">&quot;</span><span style="color:#89DDFF;">.</span><span style="color:#82AAFF;">into</span><span style="color:#89DDFF;">())),</span></span>
<span class="line"><span style="color:#A6ACCD;">        _ </span><span style="color:#89DDFF;">=&gt;</span><span style="color:#A6ACCD;"> </span><span style="color:#FFCB6B;">Ok</span><span style="color:#89DDFF;">(</span><span style="color:#A6ACCD;">courses</span><span style="color:#89DDFF;">),</span></span>
<span class="line"><span style="color:#A6ACCD;">    </span><span style="color:#89DDFF;">}</span></span>
<span class="line"><span style="color:#89DDFF;">}</span></span>
<span class="line"></span>
<span class="line"><span style="color:#F78C6C;">pub</span><span style="color:#A6ACCD;"> </span><span style="color:#F78C6C;">async</span><span style="color:#A6ACCD;"> </span><span style="color:#F78C6C;">fn</span><span style="color:#A6ACCD;"> </span><span style="color:#82AAFF;">get_course_details_db</span><span style="color:#89DDFF;">(</span></span>
<span class="line"><span style="color:#A6ACCD;">    pool</span><span style="color:#89DDFF;">:</span><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">&amp;</span><span style="color:#FFCB6B;">MySqlPool</span><span style="color:#89DDFF;">,</span></span>
<span class="line"><span style="color:#A6ACCD;">    teacher_id</span><span style="color:#89DDFF;">:</span><span style="color:#A6ACCD;"> </span><span style="color:#FFCB6B;">i32</span><span style="color:#89DDFF;">,</span></span>
<span class="line"><span style="color:#A6ACCD;">    course_id</span><span style="color:#89DDFF;">:</span><span style="color:#A6ACCD;"> </span><span style="color:#FFCB6B;">i32</span><span style="color:#89DDFF;">,</span></span>
<span class="line"><span style="color:#89DDFF;">)</span><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">-&gt;</span><span style="color:#A6ACCD;"> </span><span style="color:#FFCB6B;">Result</span><span style="color:#89DDFF;">&lt;</span><span style="color:#FFCB6B;">Course</span><span style="color:#89DDFF;">,</span><span style="color:#A6ACCD;"> </span><span style="color:#FFCB6B;">MyError</span><span style="color:#89DDFF;">&gt;</span><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">{</span></span>
<span class="line"><span style="color:#A6ACCD;">    </span><span style="color:#C792EA;">let</span><span style="color:#A6ACCD;"> row </span><span style="color:#89DDFF;">=</span><span style="color:#A6ACCD;"> </span><span style="color:#FFCB6B;">sqlx</span><span style="color:#89DDFF;">::</span><span style="color:#82AAFF;">query!</span><span style="color:#89DDFF;">(</span></span>
<span class="line"><span style="color:#A6ACCD;">        </span><span style="color:#89DDFF;">&quot;</span><span style="color:#C3E88D;">SELECT id, teacher_id, name, time</span></span>
<span class="line"><span style="color:#C3E88D;">            FROM course</span></span>
<span class="line"><span style="color:#C3E88D;">            WHERE teacher_id = ? and id = ?</span><span style="color:#89DDFF;">&quot;</span><span style="color:#89DDFF;">,</span></span>
<span class="line"><span style="color:#A6ACCD;">        teacher_id</span><span style="color:#89DDFF;">,</span></span>
<span class="line"><span style="color:#A6ACCD;">        course_id</span></span>
<span class="line"><span style="color:#A6ACCD;">    </span><span style="color:#89DDFF;">)</span></span>
<span class="line"><span style="color:#A6ACCD;">    </span><span style="color:#89DDFF;">.</span><span style="color:#82AAFF;">fetch_one</span><span style="color:#89DDFF;">(</span><span style="color:#A6ACCD;">pool</span><span style="color:#89DDFF;">)</span></span>
<span class="line"><span style="color:#A6ACCD;">    </span><span style="color:#89DDFF;">.</span><span style="color:#89DDFF;">await</span><span style="color:#89DDFF;">;</span></span>
<span class="line"></span>
<span class="line"><span style="color:#A6ACCD;">    </span><span style="color:#89DDFF;">if</span><span style="color:#A6ACCD;"> </span><span style="color:#C792EA;">let</span><span style="color:#A6ACCD;"> </span><span style="color:#FFCB6B;">Ok</span><span style="color:#89DDFF;">(</span><span style="color:#A6ACCD;">row</span><span style="color:#89DDFF;">)</span><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">=</span><span style="color:#A6ACCD;"> row </span><span style="color:#89DDFF;">{</span></span>
<span class="line"><span style="color:#A6ACCD;">        </span><span style="color:#FFCB6B;">Ok</span><span style="color:#89DDFF;">(</span><span style="color:#FFCB6B;">Course</span><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">{</span></span>
<span class="line"><span style="color:#A6ACCD;">            id</span><span style="color:#89DDFF;">:</span><span style="color:#A6ACCD;"> </span><span style="color:#FFCB6B;">Some</span><span style="color:#89DDFF;">(</span><span style="color:#A6ACCD;">row</span><span style="color:#89DDFF;">.</span><span style="color:#A6ACCD;">id</span><span style="color:#89DDFF;">),</span></span>
<span class="line"><span style="color:#A6ACCD;">            teacher_id</span><span style="color:#89DDFF;">:</span><span style="color:#A6ACCD;"> row</span><span style="color:#89DDFF;">.</span><span style="color:#A6ACCD;">teacher_id</span><span style="color:#89DDFF;">,</span></span>
<span class="line"><span style="color:#A6ACCD;">            name</span><span style="color:#89DDFF;">:</span><span style="color:#A6ACCD;"> row</span><span style="color:#89DDFF;">.</span><span style="color:#A6ACCD;">name</span><span style="color:#89DDFF;">.</span><span style="color:#82AAFF;">clone</span><span style="color:#89DDFF;">(),</span></span>
<span class="line"><span style="color:#A6ACCD;">            time</span><span style="color:#89DDFF;">:</span><span style="color:#A6ACCD;"> </span><span style="color:#FFCB6B;">Some</span><span style="color:#89DDFF;">(</span><span style="color:#A6ACCD;">row</span><span style="color:#89DDFF;">.</span><span style="color:#A6ACCD;">time</span><span style="color:#89DDFF;">.</span><span style="color:#82AAFF;">unwrap</span><span style="color:#89DDFF;">()),</span></span>
<span class="line"><span style="color:#A6ACCD;">        </span><span style="color:#89DDFF;">})</span></span>
<span class="line"><span style="color:#A6ACCD;">    </span><span style="color:#89DDFF;">}</span><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">else</span><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">{</span></span>
<span class="line"><span style="color:#A6ACCD;">        </span><span style="color:#FFCB6B;">Err</span><span style="color:#89DDFF;">(</span><span style="color:#FFCB6B;">MyError</span><span style="color:#89DDFF;">::</span><span style="color:#82AAFF;">NotFound</span><span style="color:#89DDFF;">(</span><span style="color:#89DDFF;">&quot;</span><span style="color:#C3E88D;">Course didn&#39;t founded</span><span style="color:#89DDFF;">&quot;</span><span style="color:#89DDFF;">.</span><span style="color:#82AAFF;">into</span><span style="color:#89DDFF;">()))</span></span>
<span class="line"><span style="color:#A6ACCD;">    </span><span style="color:#89DDFF;">}</span></span>
<span class="line"><span style="color:#89DDFF;">}</span></span>
<span class="line"></span>
<span class="line"><span style="color:#F78C6C;">pub</span><span style="color:#A6ACCD;"> </span><span style="color:#F78C6C;">async</span><span style="color:#A6ACCD;"> </span><span style="color:#F78C6C;">fn</span><span style="color:#A6ACCD;"> </span><span style="color:#82AAFF;">post_new_course_db</span><span style="color:#89DDFF;">(</span><span style="color:#A6ACCD;">pool</span><span style="color:#89DDFF;">:</span><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">&amp;</span><span style="color:#FFCB6B;">MySqlPool</span><span style="color:#89DDFF;">,</span><span style="color:#A6ACCD;"> new_course</span><span style="color:#89DDFF;">:</span><span style="color:#A6ACCD;"> </span><span style="color:#FFCB6B;">Course</span><span style="color:#89DDFF;">)</span><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">-&gt;</span><span style="color:#A6ACCD;"> </span><span style="color:#FFCB6B;">Result</span><span style="color:#89DDFF;">&lt;</span><span style="color:#FFCB6B;">Course</span><span style="color:#89DDFF;">,</span><span style="color:#A6ACCD;"> </span><span style="color:#FFCB6B;">MyError</span><span style="color:#89DDFF;">&gt;</span><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">{</span></span>
<span class="line"><span style="color:#A6ACCD;">    </span><span style="color:#C792EA;">let</span><span style="color:#A6ACCD;"> data </span><span style="color:#89DDFF;">=</span><span style="color:#A6ACCD;"> </span><span style="color:#FFCB6B;">sqlx</span><span style="color:#89DDFF;">::</span><span style="color:#82AAFF;">query!</span><span style="color:#89DDFF;">(</span></span>
<span class="line"><span style="color:#A6ACCD;">        </span><span style="color:#89DDFF;">&quot;</span><span style="color:#C3E88D;">INSERT INTO course ( teacher_id, name)</span></span>
<span class="line"><span style="color:#C3E88D;">            VALUES ( ?, ?)</span><span style="color:#89DDFF;">&quot;</span><span style="color:#89DDFF;">,</span></span>
<span class="line"><span style="color:#A6ACCD;">        new_course</span><span style="color:#89DDFF;">.</span><span style="color:#A6ACCD;">teacher_id</span><span style="color:#89DDFF;">,</span></span>
<span class="line"><span style="color:#A6ACCD;">        new_course</span><span style="color:#89DDFF;">.</span><span style="color:#A6ACCD;">name</span><span style="color:#89DDFF;">,</span></span>
<span class="line"><span style="color:#A6ACCD;">    </span><span style="color:#89DDFF;">)</span></span>
<span class="line"><span style="color:#A6ACCD;">    </span><span style="color:#89DDFF;">.</span><span style="color:#82AAFF;">execute</span><span style="color:#89DDFF;">(</span><span style="color:#A6ACCD;">pool</span><span style="color:#89DDFF;">)</span></span>
<span class="line"><span style="color:#A6ACCD;">    </span><span style="color:#89DDFF;">.</span><span style="color:#89DDFF;">await</span><span style="color:#89DDFF;">?;</span></span>
<span class="line"></span>
<span class="line"><span style="color:#A6ACCD;">    </span><span style="color:#C792EA;">let</span><span style="color:#A6ACCD;"> row </span><span style="color:#89DDFF;">=</span><span style="color:#A6ACCD;"> </span><span style="color:#FFCB6B;">sqlx</span><span style="color:#89DDFF;">::</span><span style="color:#82AAFF;">query!</span><span style="color:#89DDFF;">(</span></span>
<span class="line"><span style="color:#A6ACCD;">        </span><span style="color:#89DDFF;">&quot;</span><span style="color:#C3E88D;">SELECT id, teacher_id, name, time</span></span>
<span class="line"><span style="color:#C3E88D;">        FROM course</span></span>
<span class="line"><span style="color:#C3E88D;">        WHERE id = ?</span><span style="color:#89DDFF;">&quot;</span><span style="color:#89DDFF;">,</span></span>
<span class="line"><span style="color:#A6ACCD;">        data</span><span style="color:#89DDFF;">.</span><span style="color:#82AAFF;">last_insert_id</span><span style="color:#89DDFF;">()</span></span>
<span class="line"><span style="color:#A6ACCD;">    </span><span style="color:#89DDFF;">)</span></span>
<span class="line"><span style="color:#A6ACCD;">    </span><span style="color:#89DDFF;">.</span><span style="color:#82AAFF;">fetch_one</span><span style="color:#89DDFF;">(</span><span style="color:#A6ACCD;">pool</span><span style="color:#89DDFF;">)</span></span>
<span class="line"><span style="color:#A6ACCD;">    </span><span style="color:#89DDFF;">.</span><span style="color:#89DDFF;">await</span><span style="color:#89DDFF;">?;</span></span>
<span class="line"><span style="color:#A6ACCD;">    </span><span style="color:#FFCB6B;">Ok</span><span style="color:#89DDFF;">(</span><span style="color:#FFCB6B;">Course</span><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">{</span></span>
<span class="line"><span style="color:#A6ACCD;">        id</span><span style="color:#89DDFF;">:</span><span style="color:#A6ACCD;"> </span><span style="color:#FFCB6B;">Some</span><span style="color:#89DDFF;">(</span><span style="color:#A6ACCD;">row</span><span style="color:#89DDFF;">.</span><span style="color:#A6ACCD;">id</span><span style="color:#89DDFF;">),</span></span>
<span class="line"><span style="color:#A6ACCD;">        teacher_id</span><span style="color:#89DDFF;">:</span><span style="color:#A6ACCD;"> row</span><span style="color:#89DDFF;">.</span><span style="color:#A6ACCD;">teacher_id</span><span style="color:#89DDFF;">,</span></span>
<span class="line"><span style="color:#A6ACCD;">        name</span><span style="color:#89DDFF;">:</span><span style="color:#A6ACCD;"> row</span><span style="color:#89DDFF;">.</span><span style="color:#A6ACCD;">name</span><span style="color:#89DDFF;">.</span><span style="color:#82AAFF;">clone</span><span style="color:#89DDFF;">(),</span></span>
<span class="line"><span style="color:#A6ACCD;">        time</span><span style="color:#89DDFF;">:</span><span style="color:#A6ACCD;"> </span><span style="color:#FFCB6B;">Some</span><span style="color:#89DDFF;">(</span><span style="color:#A6ACCD;">row</span><span style="color:#89DDFF;">.</span><span style="color:#A6ACCD;">time</span><span style="color:#89DDFF;">.</span><span style="color:#82AAFF;">unwrap</span><span style="color:#89DDFF;">()),</span></span>
<span class="line"><span style="color:#A6ACCD;">    </span><span style="color:#89DDFF;">})</span></span>
<span class="line"><span style="color:#89DDFF;">}</span></span>
<span class="line"></span></code></pre></div><p>因为我们的数据库方法返回值改变了，所以我们的 handlers 也需要更改，我们使用 map 来处理结果：如果调用数据库成功，收到 OK, map 会将返回值包装成一个 HTTP 响应，如果过程中发生错误，map 会返回一个 error，因为我们已经把相关错误接入了 MyError 这个类型，那么发生的错误就会变成 MyError ，而它实现了 ResponseError 所以会自动转化为一个 HTTP 请求返回给用户：</p><div class="language-rust"><button class="copy"></button><span class="lang">rust</span><pre><code><span class="line"><span style="color:#F78C6C;">use</span><span style="color:#FFCB6B;"> </span><span style="color:#A6ACCD;">super</span><span style="color:#89DDFF;">::</span><span style="color:#FFCB6B;">db_access</span><span style="color:#89DDFF;">::*;</span></span>
<span class="line"><span style="color:#F78C6C;">use</span><span style="color:#FFCB6B;"> </span><span style="color:#A6ACCD;">super</span><span style="color:#89DDFF;">::</span><span style="color:#FFCB6B;">error</span><span style="color:#89DDFF;">::</span><span style="color:#FFCB6B;">MyError</span><span style="color:#89DDFF;">;</span></span>
<span class="line"><span style="color:#F78C6C;">use</span><span style="color:#FFCB6B;"> </span><span style="color:#A6ACCD;">super</span><span style="color:#89DDFF;">::</span><span style="color:#FFCB6B;">state</span><span style="color:#89DDFF;">::</span><span style="color:#FFCB6B;">AppState</span><span style="color:#89DDFF;">;</span></span>
<span class="line"><span style="color:#F78C6C;">use</span><span style="color:#FFCB6B;"> actix_web</span><span style="color:#89DDFF;">::{</span><span style="color:#FFCB6B;">web</span><span style="color:#89DDFF;">,</span><span style="color:#FFCB6B;"> HttpResponse</span><span style="color:#89DDFF;">};</span></span>
<span class="line"></span>
<span class="line"><span style="color:#F78C6C;">pub</span><span style="color:#A6ACCD;"> </span><span style="color:#F78C6C;">async</span><span style="color:#A6ACCD;"> </span><span style="color:#F78C6C;">fn</span><span style="color:#A6ACCD;"> </span><span style="color:#82AAFF;">health_check_handler</span><span style="color:#89DDFF;">(</span><span style="color:#A6ACCD;">app_state</span><span style="color:#89DDFF;">:</span><span style="color:#A6ACCD;"> </span><span style="color:#FFCB6B;">web</span><span style="color:#89DDFF;">::</span><span style="color:#FFCB6B;">Data</span><span style="color:#89DDFF;">&lt;</span><span style="color:#FFCB6B;">AppState</span><span style="color:#89DDFF;">&gt;)</span><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">-&gt;</span><span style="color:#A6ACCD;"> </span><span style="color:#FFCB6B;">HttpResponse</span><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">{</span></span>
<span class="line"><span style="color:#A6ACCD;">    </span><span style="color:#82AAFF;">println!</span><span style="color:#89DDFF;">(</span><span style="color:#89DDFF;">&quot;</span><span style="color:#C3E88D;">incoming for health check</span><span style="color:#89DDFF;">&quot;</span><span style="color:#89DDFF;">);</span></span>
<span class="line"><span style="color:#A6ACCD;">    </span><span style="color:#C792EA;">let</span><span style="color:#A6ACCD;"> health_check_response </span><span style="color:#89DDFF;">=</span><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">&amp;</span><span style="color:#A6ACCD;">app_state</span><span style="color:#89DDFF;">.</span><span style="color:#A6ACCD;">health_check_response</span><span style="color:#89DDFF;">;</span></span>
<span class="line"><span style="color:#A6ACCD;">    </span><span style="color:#C792EA;">let</span><span style="color:#A6ACCD;"> </span><span style="color:#C792EA;">mut</span><span style="color:#A6ACCD;"> visit_count </span><span style="color:#89DDFF;">=</span><span style="color:#A6ACCD;"> app_state</span><span style="color:#89DDFF;">.</span><span style="color:#A6ACCD;">visit_count</span><span style="color:#89DDFF;">.</span><span style="color:#82AAFF;">lock</span><span style="color:#89DDFF;">().</span><span style="color:#82AAFF;">unwrap</span><span style="color:#89DDFF;">();</span></span>
<span class="line"><span style="color:#A6ACCD;">    </span><span style="color:#C792EA;">let</span><span style="color:#A6ACCD;"> response </span><span style="color:#89DDFF;">=</span><span style="color:#A6ACCD;"> </span><span style="color:#82AAFF;">format!</span><span style="color:#89DDFF;">(</span><span style="color:#89DDFF;">&quot;{}</span><span style="color:#C3E88D;"> </span><span style="color:#89DDFF;">{}</span><span style="color:#C3E88D;"> times</span><span style="color:#89DDFF;">&quot;</span><span style="color:#89DDFF;">,</span><span style="color:#A6ACCD;"> health_check_response</span><span style="color:#89DDFF;">,</span><span style="color:#A6ACCD;"> visit_count</span><span style="color:#89DDFF;">);</span></span>
<span class="line"><span style="color:#A6ACCD;">    </span><span style="color:#89DDFF;">*</span><span style="color:#A6ACCD;">visit_count </span><span style="color:#89DDFF;">+=</span><span style="color:#A6ACCD;"> </span><span style="color:#F78C6C;">1</span><span style="color:#89DDFF;">;</span></span>
<span class="line"><span style="color:#A6ACCD;">    </span><span style="color:#FFCB6B;">HttpResponse</span><span style="color:#89DDFF;">::</span><span style="color:#FFCB6B;">Ok</span><span style="color:#89DDFF;">().</span><span style="color:#82AAFF;">json</span><span style="color:#89DDFF;">(&amp;</span><span style="color:#A6ACCD;">response</span><span style="color:#89DDFF;">)</span></span>
<span class="line"><span style="color:#89DDFF;">}</span></span>
<span class="line"></span>
<span class="line"><span style="color:#F78C6C;">use</span><span style="color:#FFCB6B;"> </span><span style="color:#A6ACCD;">super</span><span style="color:#89DDFF;">::</span><span style="color:#FFCB6B;">models</span><span style="color:#89DDFF;">::</span><span style="color:#FFCB6B;">Course</span><span style="color:#89DDFF;">;</span></span>
<span class="line"><span style="color:#F78C6C;">pub</span><span style="color:#A6ACCD;"> </span><span style="color:#F78C6C;">async</span><span style="color:#A6ACCD;"> </span><span style="color:#F78C6C;">fn</span><span style="color:#A6ACCD;"> </span><span style="color:#82AAFF;">new_course</span><span style="color:#89DDFF;">(</span></span>
<span class="line"><span style="color:#A6ACCD;">    new_course</span><span style="color:#89DDFF;">:</span><span style="color:#A6ACCD;"> </span><span style="color:#FFCB6B;">web</span><span style="color:#89DDFF;">::</span><span style="color:#FFCB6B;">Json</span><span style="color:#89DDFF;">&lt;</span><span style="color:#FFCB6B;">Course</span><span style="color:#89DDFF;">&gt;,</span></span>
<span class="line"><span style="color:#A6ACCD;">    app_state</span><span style="color:#89DDFF;">:</span><span style="color:#A6ACCD;"> </span><span style="color:#FFCB6B;">web</span><span style="color:#89DDFF;">::</span><span style="color:#FFCB6B;">Data</span><span style="color:#89DDFF;">&lt;</span><span style="color:#FFCB6B;">AppState</span><span style="color:#89DDFF;">&gt;,</span></span>
<span class="line"><span style="color:#89DDFF;">)</span><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">-&gt;</span><span style="color:#A6ACCD;"> </span><span style="color:#FFCB6B;">Result</span><span style="color:#89DDFF;">&lt;</span><span style="color:#FFCB6B;">HttpResponse</span><span style="color:#89DDFF;">,</span><span style="color:#A6ACCD;"> </span><span style="color:#FFCB6B;">MyError</span><span style="color:#89DDFF;">&gt;</span><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">{</span></span>
<span class="line"><span style="color:#A6ACCD;">    </span><span style="color:#82AAFF;">post_new_course_db</span><span style="color:#89DDFF;">(&amp;</span><span style="color:#A6ACCD;">app_state</span><span style="color:#89DDFF;">.</span><span style="color:#A6ACCD;">db</span><span style="color:#89DDFF;">,</span><span style="color:#A6ACCD;"> new_course</span><span style="color:#89DDFF;">.</span><span style="color:#82AAFF;">into</span><span style="color:#89DDFF;">())</span></span>
<span class="line"><span style="color:#A6ACCD;">        </span><span style="color:#89DDFF;">.</span><span style="color:#89DDFF;">await</span></span>
<span class="line"><span style="color:#A6ACCD;">        </span><span style="color:#89DDFF;">.</span><span style="color:#82AAFF;">map</span><span style="color:#89DDFF;">(|</span><span style="color:#A6ACCD;">course</span><span style="color:#89DDFF;">|</span><span style="color:#A6ACCD;"> </span><span style="color:#FFCB6B;">HttpResponse</span><span style="color:#89DDFF;">::</span><span style="color:#FFCB6B;">Ok</span><span style="color:#89DDFF;">().</span><span style="color:#82AAFF;">json</span><span style="color:#89DDFF;">(</span><span style="color:#A6ACCD;">course</span><span style="color:#89DDFF;">))</span></span>
<span class="line"><span style="color:#89DDFF;">}</span></span>
<span class="line"></span>
<span class="line"><span style="color:#F78C6C;">pub</span><span style="color:#A6ACCD;"> </span><span style="color:#F78C6C;">async</span><span style="color:#A6ACCD;"> </span><span style="color:#F78C6C;">fn</span><span style="color:#A6ACCD;"> </span><span style="color:#82AAFF;">get_courses_for_teacher</span><span style="color:#89DDFF;">(</span></span>
<span class="line"><span style="color:#A6ACCD;">    app_state</span><span style="color:#89DDFF;">:</span><span style="color:#A6ACCD;"> </span><span style="color:#FFCB6B;">web</span><span style="color:#89DDFF;">::</span><span style="color:#FFCB6B;">Data</span><span style="color:#89DDFF;">&lt;</span><span style="color:#FFCB6B;">AppState</span><span style="color:#89DDFF;">&gt;,</span></span>
<span class="line"><span style="color:#A6ACCD;">    params</span><span style="color:#89DDFF;">:</span><span style="color:#A6ACCD;"> </span><span style="color:#FFCB6B;">web</span><span style="color:#89DDFF;">::</span><span style="color:#FFCB6B;">Path</span><span style="color:#89DDFF;">&lt;(</span><span style="color:#FFCB6B;">usize</span><span style="color:#89DDFF;">,)&gt;,</span></span>
<span class="line"><span style="color:#89DDFF;">)</span><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">-&gt;</span><span style="color:#A6ACCD;"> </span><span style="color:#FFCB6B;">Result</span><span style="color:#89DDFF;">&lt;</span><span style="color:#FFCB6B;">HttpResponse</span><span style="color:#89DDFF;">,</span><span style="color:#A6ACCD;"> </span><span style="color:#FFCB6B;">MyError</span><span style="color:#89DDFF;">&gt;</span><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">{</span></span>
<span class="line"><span style="color:#A6ACCD;">    </span><span style="color:#C792EA;">let</span><span style="color:#A6ACCD;"> teacher_id </span><span style="color:#89DDFF;">=</span><span style="color:#A6ACCD;"> </span><span style="color:#FFCB6B;">i32</span><span style="color:#89DDFF;">::</span><span style="color:#82AAFF;">try_from</span><span style="color:#89DDFF;">(</span><span style="color:#A6ACCD;">params</span><span style="color:#89DDFF;">.</span><span style="color:#F78C6C;">0</span><span style="color:#89DDFF;">).</span><span style="color:#82AAFF;">unwrap</span><span style="color:#89DDFF;">();</span></span>
<span class="line"><span style="color:#A6ACCD;">    </span><span style="color:#82AAFF;">get_courses_for_teacher_db</span><span style="color:#89DDFF;">(&amp;</span><span style="color:#A6ACCD;">app_state</span><span style="color:#89DDFF;">.</span><span style="color:#A6ACCD;">db</span><span style="color:#89DDFF;">,</span><span style="color:#A6ACCD;"> teacher_id</span><span style="color:#89DDFF;">)</span></span>
<span class="line"><span style="color:#A6ACCD;">        </span><span style="color:#89DDFF;">.</span><span style="color:#89DDFF;">await</span></span>
<span class="line"><span style="color:#A6ACCD;">        </span><span style="color:#89DDFF;">.</span><span style="color:#82AAFF;">map</span><span style="color:#89DDFF;">(|</span><span style="color:#A6ACCD;">courses</span><span style="color:#89DDFF;">|</span><span style="color:#A6ACCD;"> </span><span style="color:#FFCB6B;">HttpResponse</span><span style="color:#89DDFF;">::</span><span style="color:#FFCB6B;">Ok</span><span style="color:#89DDFF;">().</span><span style="color:#82AAFF;">json</span><span style="color:#89DDFF;">(</span><span style="color:#A6ACCD;">courses</span><span style="color:#89DDFF;">))</span></span>
<span class="line"><span style="color:#89DDFF;">}</span></span>
<span class="line"></span>
<span class="line"><span style="color:#F78C6C;">pub</span><span style="color:#A6ACCD;"> </span><span style="color:#F78C6C;">async</span><span style="color:#A6ACCD;"> </span><span style="color:#F78C6C;">fn</span><span style="color:#A6ACCD;"> </span><span style="color:#82AAFF;">get_course_detail</span><span style="color:#89DDFF;">(</span></span>
<span class="line"><span style="color:#A6ACCD;">    app_state</span><span style="color:#89DDFF;">:</span><span style="color:#A6ACCD;"> </span><span style="color:#FFCB6B;">web</span><span style="color:#89DDFF;">::</span><span style="color:#FFCB6B;">Data</span><span style="color:#89DDFF;">&lt;</span><span style="color:#FFCB6B;">AppState</span><span style="color:#89DDFF;">&gt;,</span></span>
<span class="line"><span style="color:#A6ACCD;">    params</span><span style="color:#89DDFF;">:</span><span style="color:#A6ACCD;"> </span><span style="color:#FFCB6B;">web</span><span style="color:#89DDFF;">::</span><span style="color:#FFCB6B;">Path</span><span style="color:#89DDFF;">&lt;(</span><span style="color:#FFCB6B;">usize</span><span style="color:#89DDFF;">,</span><span style="color:#A6ACCD;"> </span><span style="color:#FFCB6B;">usize</span><span style="color:#89DDFF;">)&gt;,</span></span>
<span class="line"><span style="color:#89DDFF;">)</span><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">-&gt;</span><span style="color:#A6ACCD;"> </span><span style="color:#FFCB6B;">Result</span><span style="color:#89DDFF;">&lt;</span><span style="color:#FFCB6B;">HttpResponse</span><span style="color:#89DDFF;">,</span><span style="color:#A6ACCD;"> </span><span style="color:#FFCB6B;">MyError</span><span style="color:#89DDFF;">&gt;</span><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">{</span></span>
<span class="line"><span style="color:#A6ACCD;">    </span><span style="color:#C792EA;">let</span><span style="color:#A6ACCD;"> teacher_id </span><span style="color:#89DDFF;">=</span><span style="color:#A6ACCD;"> </span><span style="color:#FFCB6B;">i32</span><span style="color:#89DDFF;">::</span><span style="color:#82AAFF;">try_from</span><span style="color:#89DDFF;">(</span><span style="color:#A6ACCD;">params</span><span style="color:#89DDFF;">.</span><span style="color:#F78C6C;">0</span><span style="color:#89DDFF;">).</span><span style="color:#82AAFF;">unwrap</span><span style="color:#89DDFF;">();</span></span>
<span class="line"><span style="color:#A6ACCD;">    </span><span style="color:#C792EA;">let</span><span style="color:#A6ACCD;"> course_id </span><span style="color:#89DDFF;">=</span><span style="color:#A6ACCD;"> </span><span style="color:#FFCB6B;">i32</span><span style="color:#89DDFF;">::</span><span style="color:#82AAFF;">try_from</span><span style="color:#89DDFF;">(</span><span style="color:#A6ACCD;">params</span><span style="color:#89DDFF;">.</span><span style="color:#F78C6C;">1</span><span style="color:#89DDFF;">).</span><span style="color:#82AAFF;">unwrap</span><span style="color:#89DDFF;">();</span></span>
<span class="line"><span style="color:#A6ACCD;">    </span><span style="color:#82AAFF;">get_course_details_db</span><span style="color:#89DDFF;">(&amp;</span><span style="color:#A6ACCD;">app_state</span><span style="color:#89DDFF;">.</span><span style="color:#A6ACCD;">db</span><span style="color:#89DDFF;">,</span><span style="color:#A6ACCD;"> teacher_id</span><span style="color:#89DDFF;">,</span><span style="color:#A6ACCD;"> course_id</span><span style="color:#89DDFF;">)</span></span>
<span class="line"><span style="color:#A6ACCD;">        </span><span style="color:#89DDFF;">.</span><span style="color:#89DDFF;">await</span></span>
<span class="line"><span style="color:#A6ACCD;">        </span><span style="color:#89DDFF;">.</span><span style="color:#82AAFF;">map</span><span style="color:#89DDFF;">(|</span><span style="color:#A6ACCD;">course</span><span style="color:#89DDFF;">|</span><span style="color:#A6ACCD;"> </span><span style="color:#FFCB6B;">HttpResponse</span><span style="color:#89DDFF;">::</span><span style="color:#FFCB6B;">Ok</span><span style="color:#89DDFF;">().</span><span style="color:#82AAFF;">json</span><span style="color:#89DDFF;">(</span><span style="color:#A6ACCD;">course</span><span style="color:#89DDFF;">))</span></span>
<span class="line"><span style="color:#89DDFF;">}</span></span>
<span class="line"></span></code></pre></div><p>最后我们运行测试用例，如果允许均通过，说明我们的错误处理编写成功。</p><p>最后我们启动我们的服务器，然后尝试访问一个不存在 id ，比如 <code>http://localhost:3000/courses/1111</code> ，如果返给你如下的响应，说明你的项目编写成功了：</p><div class="language-json"><button class="copy"></button><span class="lang">json</span><pre><code><span class="line"><span style="color:#89DDFF;">{</span></span>
<span class="line"><span style="color:#A6ACCD;">    </span><span style="color:#89DDFF;">&quot;</span><span style="color:#C792EA;">error_message</span><span style="color:#89DDFF;">&quot;</span><span style="color:#89DDFF;">:</span><span style="color:#A6ACCD;"> </span><span style="color:#89DDFF;">&quot;</span><span style="color:#C3E88D;">Course not found for teacher</span><span style="color:#89DDFF;">&quot;</span></span>
<span class="line"><span style="color:#89DDFF;">}</span></span>
<span class="line"></span></code></pre></div><h2 id="说明" tabindex="-1">说明 <a class="header-anchor" href="#说明" aria-hidden="true">#</a></h2><p>本教程只是作者的学习笔记，帮助理解和记忆 RUST 开发，课程全部来源是 B站 杨旭老师的教程：</p><p><a href="https://www.bilibili.com/video/BV1RP4y1G7KF?p=1&amp;vd_source=8595fbbf160cc11a0cc07cadacf22951" target="_blank" rel="noreferrer">https://www.bilibili.com/video/BV1RP4y1G7KF?p=1&amp;vd_source=8595fbbf160cc11a0cc07cadacf22951</a></p><p>教学 demo 可以查看大佬的 git：</p><p><a href="https://github.com/FrancisYLfan/rust_web_server_from_yang" target="_blank" rel="noreferrer">https://github.com/FrancisYLfan/rust_web_server_from_yang</a></p></div></div></main><!--[--><!--]--><footer class="VPDocFooter" data-v-37ebe389 data-v-a54a85bd><!----><div class="prev-next" data-v-a54a85bd><div class="pager" data-v-a54a85bd><a class="pager-link prev" href="/articles/rustweb/03.%E8%BF%9E%E6%8E%A5%E6%95%B0%E6%8D%AE%E5%BA%93.html" data-v-a54a85bd><span class="desc" data-v-a54a85bd>Previous page</span><span class="title" data-v-a54a85bd>03.连接数据库</span></a></div><div class="has-prev pager" data-v-a54a85bd><a class="pager-link next" href="/articles/rustweb/05.%E5%AE%8C%E6%95%B4%E9%A1%B9%E7%9B%AE%E9%87%8D%E6%9E%84.html" data-v-a54a85bd><span class="desc" data-v-a54a85bd>Next page</span><span class="title" data-v-a54a85bd>05.完整项目重构</span></a></div></div></footer><!--[--><!--]--></div></div></div></div></div><!----><!--[--><!--]--></div></div>
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